Chapter III

THE GRADES OF THE FACTORS OF EVOLUTION AND THE ORDER OF THEIR
APPEARANCE.

_Factors of evolution restated; their grades and the order of
their introduction shown_--Lamarckian factors, first
in order because they precede sexual reproduction--(1)
Environment--(2) Use and disuse--With sexual reproduction
selective factors introduced--(3) Natural selection--(4)
Physiological selection--(5) Sexual selection--With man
was introduced (6) the rational factor--In this process
two striking stages--viz., the introduction of sex and the
introduction of reason--Effect of each to hasten the steps of
evolution--The last by far the greater change 81

_Contrast between organic and human evolution_--(1) The
meaning of term _fittest_ in each--(2) Destiny of the
weak and helpless in each--(3) The nature of evolutionary
transformation in each--(4) The law of strait and narrow way
applied in each--(5) Human evolution is a different kind and
on a higher plane 88

_Application to some questions of the day._

I. Neo-Darwinists, their position explained--Reasons for
dissenting--(_a_) Lamarckian factors preceded all others--
(_b_) Though now subordinate, they still underlie and condition
all other factors--(_c_) Shown by comparison of phylogeny
with ontogeny 92

II. Human progress not identical with organic evolution--Mistake
of the materialists--But neither is it wholly different, as
some suppose 96

III. Neo-Darwinism is fatal to hopes of human progress--Reason
may use freely Lamarckian factors, but can not use natural
selection in the same way as Nature does 97

CHAPTER IV.

SPECIAL PROOFS FROM THE GENERAL LAWS OF ANIMAL STRUCTURE, OR
COMPARISON IN THE TAXONOMIC SERIES.

_General Principles._

_Analogy and homology_--Defined and illustrated by examples--
Wings and limbs--Lungs, gradual formation of, traced in the
Taxonomic series--Traced in the Ontogenic series--Examples
of homology in plants: tuber, cactus-leaf, acacia-leaf--
Definitions repeated and further explained--Common origin is
the only explanation of homology 99

_Primary divisions of the animal kingdom_--True ground of such
divisions is ability to trace homology--We take examples
only from vertebrata and articulata--Compare to styles of
architecture--To machines--To branching stem 107